The first so-called “smart gun” has hit the shelves at U.S. retail outlets, including one of the biggest firearms stores in California, according to theWashington Post.

The Smart System iP1, a .22-caliber pistol made by the German gun-maker Armatix GmbH, can only function with an accompanying wristwatch, which is sold separately.

When the RFID-equipped watch is activated by a PIN number and placed near the gun — like when a shooter grips the handle — it sends a signal to unlock the gun and a light on the back of the weapon turns green, according to the report. Otherwise, the firearm stays locked and the light on the back remains red, it stated.

The pistol sells for $1,399 and the watch retails for another $399 — more than double the cost of .40-caliber Glock handgun, according to the article.

The company is betting that demand for the technology will increase as consumers seek guns modified for safety.

Winkdex: the name sounds like an X-rated cleaning product. But that doesn’t mean the latest brainchild from the Winklevoss twins is a bad idea.

As the New York Times reported, the Winkdex (ugh!) launched on Wednesday, and offers Bitcoin watchers a new way to track the value of the currency, by blending the value of three top currency exchanges. It looks like this:

The website has the potential to be an important new pricing metric since the cost of a bitcoin has historically varied significantly between one exchange and the next. And while other sites, like Coinbase and Bitstamp, offer price trackers too, their charts are less detailed and transparent. The Winkdex price is based on a formula based on the highest exchanges by volume (Mt. Gox, recently the biggest exchange in the world, is excluded due to its recent troubles.)

Facebook (s fb) will acquire messaging company WhatsApp for $16 billion, according to an SEC filing Wednesday. The purchase price includes roughly $4 billion in cash and $12 billion in Facebook stock. An additional $3 billion in restricted stock could be paid out over four years to WhatsApp employees.

In a blog post, Facebook pointed to some numbers to help illustrate its decision to acquire WhatsApp. The app has 450 million active users, 70 percent of whom are active in a given day, and is adding over a million new registered users each day. And messaging volume within the app is approaching levels equal to SMS messaging globally. That level of adoption seems to be the clincher for Facebook, which…

BitTag is a physical price tag that creates a seamless integration between Bitcoin (or any another cryptocurrency) transactions and “bricks and mortar” retail stores.

Once set up, the BitTag hardware displays information such as the product name, price in USD (or other local currencies) and the real-time price in Bitcoin. If the Bitcoin value suddenly fluctuates, the price on BitTag will instantly reflect this. The customer, therefore, instantly knows how much the item is worth, whilst the retailer does not incur any financial loss if the value of the Bitcoin changes.

Each BitTag is managed with the assistance of an accompanying iPad app. The app can either be used to setup the Tag or process a Bitcoin transaction by simply placing the BitTag on the screen. Alternatively, the Bitcoin transaction can be activated by a simple ‘shake’ of the BitTag, enabling a Bitcoin QR code to be displayed on…